2018-2019 Influenza Season Update for Week 10*
(The week ending on Saturday, March 9, 2019)
Key Points
Classification of Connecticut geographic activity remains at widespread** for week 10.
Influenza activity appears to have peaked but remains elevated nationally and within Connecticut.
Influenza A viruses are the predominate type circulating; very few flu B viruses are now being reported.
The U.S. Centers for Disease Control and Prevention (CDC) recent reports on the percentage of people
nationally seeing their health care provider with influenza-like-illness (ILI) is currently 4.7%, above the
national baseline of 2.2% for elevated ILI activity.
There is still time for you and your family to obtain your flu vaccine and take steps to prevent influenzarelated illness and hospitalization:
https://portal.ct.gov/DPH/Immunizations/Seasonal-Influenza
The Department of Public Health (DPH) uses multiple surveillance systems to monitor circulating flu viruses
throughout the year. Data are updated with available information each week starting in October and ending in
May. Consider current week data preliminary due to delays in reporting and confirmation.
The percentage of statewide emergency department visits attributed to the ?fever/flu syndrome? has
decreased from 8.4% in week 9 to 7.8% in week 10 (Figure 1). Caution should be used when comparing the
2018-2019 EpiCenter syndromic surveillance data to 2016-2017 and 2017-2018 Hospital Emergency
Department Syndromic Surveillance System data?
.
The percentage of outpatient visits with influenza-like illness (ILI) has recently decreased to 4.9%, above
the level of 1% generally considered the minimum threshold for elevated influenza-associated visits in the
outpatient setting in Connecticut (Figure 2).
To date, a total of 2,303 hospitalized patients with laboratory-confirmed influenza admitted during the
current season (August 26 to March 9, 2019) have been reported. Of these, 1,980 were associated with type
A (subtype unspecified), 213 influenza A (2009 H1N1), 75 influenza A (H3N2), and 35 influenza B viruses
(Figures 3 & 4).
Four flu-associated deaths were reported in week 10, resulting in a total of 44 deaths reported in Connecticut
during this flu season so far. Thirty-eight flu-associated deaths were associated with influenza A
(unspecified), 4 with influenza A (2009 H1N1), 1 with influenza A (H3N2), and 1 with influenza B. Of the
44 total reported flu-associated deaths, 27 occurred in persons >65 years of age, 12 in persons 50-64 years
of age, 4 in persons 25-49 years of age, and 1 in an individual 5-17 years of age.
A total of 6,595 influenza positive laboratory tests have been reported during the current season: New
Haven (2,048), Hartford County (1,509), Fairfield (1,357), New London (524), Litchfield (400), Middlesex
(388), Windham (223), Tolland (121), and 25 in currently unknown counties. Of the 6,595 total positive
reports, 5,559 were influenza A (subtype unspecified), 723 influenza A (2009 H1N1), 187 influenza A
(H3N2), and 126 influenza B (Figures 5 & 6).
Three additional figures are included in this week?s update. Since 2003, the Connecticut Emerging
Infections Program (EIP) at the Yale School of Public Health conducts active surveillance for laboratory
confirmed, influenza-associated hospitalizations as part of the national FluSurv-NET system. EIP staff work
with the Connecticut Department of Public Health, the Centers for Disease Control and Prevention, and
local hospitals to conduct surveillance for hospitalized cases of influenza among residents of New Haven
and Middlesex Counties. Together with other FluSurv-NET sites, these data provide near real time estimates
of influenza severity in the US:
https://publichealth.yale.edu/eip/projects/flu.aspx.
o Figure 7 displays total New Haven and Middlesex County resident hospitalizations by MMWR
week* and age category (includes preliminary counts for week 11 as of March 13, 2019). Please
note that the vast majority of hospitalizations are among residents greater than 65 years of age.
o Figure 8 displays total New Haven and Middlesex County resident hospitalizations by MMWR
week* and flu type (includes preliminary counts for week 11 as of March 13, 2019). The majority
of hospitalizations among New Haven and Middlesex County residents are associated with
influenza A infections.
o Figure 9 compares the current 2018-2019 influenza season New Haven and Middlesex County
resident hospitalizations with those of the previous two influenza seasons (2017-2018 and 2016-
2017).
https://portal.ct.gov/-/media/Depar...ases/flu/stats/flusummary_1819_wk10.pdf?la=en